Using a text editing program (like Notepad or Wordpad), create a file with the following PHP redirect on your computer. After Location:, enter the URL that you want to redirect the website to (for example, http://www.yourdomain.com/).

<?
header("Location: URL");
exit;
?>

Using the example link, the full script would look as follows:

<?php
header("Location: http://www.yourdomain.com/");
?>

Save this file as index.php.

Log in to your new subdomain's FTP server.

Navigate to the /www.yourdomain.com/web/content directory.

Upload the index.php into this folder.
The redirect should be fully functional.